In the cotton industry, the process of strapping a bale has been, for the most part, transitioned from using humans to manually tie bales to using automated machines to automatically strap bales. In the cotton or fiber industry, there are generally three ways in which to secure a bale after the bale has been pressed. These three ways include: pre-formed steel wires having interlocking ends, flat ribbon-steel bands having their ends inserted into a crimp and crimped and flat thermoplastic strapping material that are welded together.
Pre-formed steel wires may be tied by pivotally mounted wire bend assemblies which take the place of workers on each side of the baling press. The workers bend the tie wires around a bale by inserting the ends of the tie wires into a wire tie guide assembly. However, workers are still required to individually load each of a plurality of tie wires into the wire bend assemblies.
Bale tying using flat steel straps is hindered primarily by the cost of the strapping material, the complexity of the machinery used, and the speed at which the machinery is able to operate. In addition, the sheer weight of the steel strap tie material and its substantially sharp edges make the material cumbersome and dangerous to handle.
Conversely, plastic or other non-ferrous material is ideal for strapping bales of cotton or other fibers. Plastic is relatively lightweight, can be formed into a variety of widths and thicknesses and has relatively soft edges, allowing for easy handling and lower shipping costs. Plastic or other non-ferrous strapping material is competitive with wire ties on a cost per bale basis and is easily adaptable to fully automatic tying machinery. Additionally, plastic or other non-ferrous strapping material is readily recyclable by the end user and is considered substantially safer than steel strapping material, particularly in instances of strap breakage.
Generally, automatic bale strapping device are categorized as up-packers, wherein baling chambers reside underneath the bale strapping device, often under the floor or ground, and down-packers, wherein baling chambers are located above the bale strapping device. Down-packers can also incorporate doors instead of enclosed bale chambers.
Down-packer-type presses are generally less expensive to purchase and install as much, if not all, of the work is done above ground. However, a down-packer-type press tends to give up some performance advantages, namely, cycle time or bales-per-hour.
Bale strapping systems for feeding straps over a pressed bale and then welding the two ends of each strap together to produce a strapped bale are well known. Exemplary bale strapping systems are disclosed in U.S. Pat. Nos. 7,841,272 and 6,536,336, the contents of which are expressly incorporated herein by reference for all purposes. A strapped bale typically has 6 or 8 straps. In practice, three serially connected bale strap assemblies in a bale strapping system can produce three straps at a time and then indexed to another section of the same bale to produce three additional straps for a total of six straps. For an eight-strap system, four bale strap assemblies are typically used with indexing to form eight straps. A bale strapping system may also include six or eight bale strap assemblies to produce all of the straps in the same strapping procedure.
As disclosed in the '272 and '336 patents, each bale strap assembly has numerous moving parts and parts that rotate about respective pivot pins. When these parts operate at high speed and cycle over and over during normal service, the parts can wear and sometimes prematurely if not correctly set or aligned.